Spray booms are known in the art for use in association with various agricultural pursuits, including spraying plants with fertilizer, herbicide and the like. Such systems typically involve a generally horizontal boom provided with several sprayers. It is desirable to provide a spray boom with as many depending implements as possible, to treat as many rows as possible, during a single pass of the spray boom. As it is difficult to move very large spray booms on the highway, most spray booms are designed with a folding capability, which allows the spray boom to be folded for transport and extended for use. Spray booms can extend one hundred and twenty feet or more in width. While wider spray booms cover more land with each pass, they increase the likelihood the spray boom will encounter something unusual in its path. On uneven terrain, the spray boom may encounter hills or valleys that place the crop closer or farther away from the spray boom. The spray boom may also encounter areas of crops growing at a faster or slower rate, placing the tops of the crops closer or farther away from the boom. Fences, trees or other obstructions may also be in the path of the tips of the spray boom, posing a threat of damage to the spray boom if the boom is not moved.
Modern spray booms are provided with hydraulic lifts to move the spray booms up and down as desired, as well as with a tilt feature to tilt the booms relative to the support vehicles when the spray booms are operated on sloped surfaces. It is also known to provide the spray booms with hydraulic actuators that fold the sections of the spray booms for transport. While it would be possible to manually tilt and fold a spray boom to avoid obstacles, this system has two drawbacks. First, it would be difficult for an operator, especially with a very wide boom to maintain vigilant watch over the entire path of the spray boom. While the operator was busy adjusting the tilt or extension of one side of the boom, the other side of the boom would not be attended. Second, from the cab to the tips of the spray boom, it would be difficult to estimate the distance the spray boom should be moved up or down. While some adjustment may be better than no adjustment, some efficiency potential is still lost with manual adjustments.
Automatic spray boom adjustment systems are known in the art. Heiniger et al. U.S. Pat. No. 5,350,228 discloses a spray boom with automatic boom end height control. Streilioff et al U.S. Pat. No. 6,836,223 discloses an automatic system for tilting a spray boom. Such prior art patents use ultrasonic transducers or the like to bounce signals off the ground directly below the transducers. From the bounced signals, the systems are able to calculate the distance of the boom from the ground and tilt the boom accordingly to avoid contact with the ground.
One drawback associated with such prior art devices is that by the time the system receives the bounced signal, the transducer is already passed the point where the distance to the ground was measured. While such systems allow for the movement of the boom in relation to the changing terrain, the adjustments are being made relative to ground that has already been covered. While it is possible to extend the transducer slightly forward of the spray boom, extension more than a meter makes the transducer susceptible to undesirable vibration which can add error to the ground distance calculations. Even if the transducer is extended forward, unless the agricultural vehicle operates at a very slow speed, by the time the hydraulics associated with the spray booms readjust the orientation of the spray boom, the spray boom has already covered the area of ground measured by the transducer.
It would, therefore, be desirable to provide an articulated spray boom system which allows an agricultural vehicle with a spray boom to operate at a higher speed, measure an area in front of a spray boom and adjust the orientation of the spray boom before the spray boom reaches the measured area. The prior art difficulties described hereinabove are substantially eliminated by the present invention.